Adjusting a Shaper Spindle

A bent spindle, bad bushings, or worn spacers could cause a shaper to wobble and make sloppy cuts. Here's advice on making precise adjustments or repairs. January 2, 2012

Question
My friend just set up a used shaper and ran a glue joint knife (Freeborn carbide) and ended up with quite a bit of play in the joint. I can only think that his 1" spindle might be a little bent causing run-out. Does anyone else have other possibilities or can confirm my suspicions? He is quite disappointed.

Forum Responses
(Solid Wood Machining Forum)
From contributor D:
Setting up a good glue joint is a little more complicated than most people think. Verifying your fences are parallel is first. Then set it up like your jointer, removing a very tiny bit on the infeed side to insure what you're cutting is the whole profile of the cutter. The outfeed fence needs to be exactly the same distance from the spindle as the cut stock.

Checking your spindle for runout could have been done before purchase. Just slap down a mag base dial indicator with the spring loaded tip against the highest part of the shaft, and turn the shaft by hand. The less the needle moves, the better. This is not a bad idea these days to check even new machines. You never know. Smaller diameter cutters and brand new spacers will help before replacing the shaft, which is not really that big of a deal.

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From the original questioner:
I just talked to my friend and he said he solved the problem by replacing the spindle spacers below the knives. They must have been worn or abused enough to cause a problem. Thanks for the in-put.

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From contributor K:
Congrats on finding the problem quickly. I thought I had a bent spindle as well while using a glue joint cutter. Switching to another spindle and using a dial indicator and magnetic base attached to the spindle showed the same problem. It would seem that I need to shim the spindle housing from underneath the table to bring it back to 90 degrees in all planes. Does anyone have tips on the best way to do this, i.e., shim stock type/material, torque specs on the bolts, etc.?

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From contributor U:
Shaper setup is a big deal and might have been your problem. As for the bent spindle, I thought I had one until I checked the spacers from Freeborn, they were the problem. Putting a dial indicator against the shaft and rotating by hand showed no needle movement, as in zero. I bought new spacers and problem solved.

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From contributor L:
To confirm your spindle is perpendicular, the easiest way I have found is to place a magnetic based dial indicator on the end of the spindle. After confirming that the spindle is not bent as mentioned, it is possible to have a straight spindle and bad bushings. I have seen many times spindles that will run untrue when loaded and true when unloaded all due to inconsistent bushings.

Rotate the spindle, the indicator should move very little. Make several rotations slowly and note the values throughout the rotation. Then reverse direction and repeat. Look at your data and determine where your highs and lows are. I have seen on some machines with weak castings and the table itself will not be true, but I’m assuming this is not the case. What I use to shim a spindle mount is actual feeler gauges. Just be sure any shimming done must be balanced. If you only shim one side of a bolt, it will pull the casting unbalanced and create stress.